In industrial sites, mechanical pressure switches can ensure safe pressure monitoring in pumps, compressors and mobile working machinery, so it is particularly important to require a pressure calibration bench to verify and calibrate them. Regardless of the application, these mechanical pressure switches work on the principle of a preloaded spring and use a diaphragm or piston as the pressure measuring element.

Under this working principle, two forces act:
1. Process pressure
The measuring element of the pressure switch responds to the process pressure value. Therefore, the meter is designed in two ways. At lower process pressures, mechanical pressure switches use a diaphragm (because of the larger surface area to absorb the pressure), while at higher pressures, mechanical pressure switches use a piston with a smaller surface area.
2. Preload spring force
Adjust the spring force by adjusting the screw of the pressure switch. The further the screw is screwed in, the greater the spring force the measuring element has to overcome and the switching point value increases accordingly. The spring geometry is designed according to the desired switching range. According to the functional principle of the mechanical pressure switch, the switching point is defined by the spring preload. It sets the switch point of the switch when the pressure increases and the reset point of the switch when the pressure decreases.